1. Field of the Invention
The present invention relates to an impact crusher having a support member subject to rotational motion during the operation of the crusher, and carrying a breaker bar which is subject to centrifugal forces and employed for comminuting particulate material, such as rock, ore, limestone, grain, concrete or the like. More particularly, it pertains to an improved means for securing the breaker bar to the support member.
2. Description of the Prior Art
In impact crushers, it is well known to provide a rotor with several replaceable breaker or impact bars mounted onto the periphery of the rotor, which may be of the open disc-type consisting of generally several discs mounted on a rotatable shaft. In the present open disc-type rotor, both the back-up bar and breaker bar extend between opposed discs. The back-up bar is welded in the opposed discs, and may either have an angular protrusion which fits into a similarly formed depression in the breaker bar as shown in U.S. Pat. No. 3,531,055 or may have an angularly formed depression for receiving a similarly formed protrusion of the breaker bar. The breaker bar is held in position by inserting a breaker bar holder or shoe against a nose of the disc between the breaker bar and disc.
During rotation of the shaft and discs, severe centrifugal forces are exerted against the sloped protrusions and depressions in the breaker bar or back-up bar, and/or severe lateral forces are ultimately exerted against the shoe resulting in a skewed seating for the breaker bar, and thus, reduced contact support between the breaker bar with a bottom edge of the shoe and also between the breaker bar with an upper edge of the back-up bar and between the depression and protrusion area of the breaker bar and back-up bar to the extent that there will exist insufficient support and eventual damage to the back-up bar protrusion and the disc nose.
Also, in the past designs due to the environment under which the machine is operated, the constant pounding and the centrifugal forces, the removal of the breaker bar results in a costly, time-consuming, and exertful task.
This present design for replaceable breaker bars is extremely unconducive in establishing and maintaining self-alignment of the back-up bar, breaker bar, and shoe, and frequently results in deformation of the back-up bar and the rotor disc nose which are normally considered to be non-replaceable components. This deformation condition of the back-up bar and disc nose often requires repair by weld built-up or machining of these fixed parts, which translates into extended downtime of the impact crusher and excessive maintenance manpower hours.
Other mounting arrangments for the breaker bar of the open disc type rotor assemblies for impact crushers have developed such as that disclosed in the applicant's patent application bearing U.S. Ser. No. 596,210 filed Apr. 2, 1984, which recently has been allowed and in German patent application No. 2,916,649 filed Apr. 25, 1979; the latter arrangement still having the tendency to cause a skewed seating for the breaker bar which tendency has been eliminated in the former reference. In spite of these foregoing arrangements there remains a need for an improved mechanism for mounting the breaker bar in the discs of the impact crushers.